Water: Our Most Important Natural Resource

© The GlobalEd 2 Project

Essential Questions:

1. How much of our planet is covered by water?

2. Why is fresh water so important?

3. How much fresh water is on earth?

4. So, why can’t we just drink sea water?

© The GlobalEd 2 Project

Enduring Understandings:

1. ~70% of the Earth’s surface is covered by water.2. ~70% of the human body is made up of water; fresh

water is essential for the survival of all ecosystems; a person can only live without water for ~2-4 days; but can live without food for weeks.

3. There is a limited amount of fresh water on Earth.4. The high concentration of salt in seawater can lead to

heart failure and even death.

© The GlobalEd 2 Project

Types of Water

• Salt water (contains ~ 3.5% NaCl) Major sources – oceans, seas *~ 97% of Earth’s water is salt water

• Fresh Water (contains ~ < 1% NaCl) Major sources – ponds, lakes, rivers, streams;

precipitation from the atmosphere, as mist, rain or snow

© The GlobalEd 2 Project

Fresh Water • Only ~ 2.75% water on Earth is fresh water!• ~ 2/3 of that is frozen in glaciers• ~ 1/4 is groundwater• Only ~ 0.005% is surface water * Hence, less than 1% is fresh water that we

can actually use• Fresh water lakes (i.e., Lake Baikal in Russia

and the Great Lakes in North America), contain 7/8 of this fresh surface water

© The GlobalEd 2 Project

Interpreting:

Read the following sailor’s poem; explain the author’s meaning.

“Water, water, everywhere,

And all the boards did shrink;

Water, water, everywhere,

Nor any drop to drink."

(from Samuel Taylor Coleridge's The Rime of the Ancient Mariner)

© The GlobalEd 2 Project